Stopping pegloticase in patients who have pre-infusion uric acid levels higher than 6 mg/dL while on therapy would prevent most infusion reactions.

Preinfusion serum uric acid levels may be an effective biomarker for identifying patients at risk for infusion reactions while receiving pegloticase, according to study results published in Rheumatology and Therapy.

Researchers analyzed data from two phase 3 clinical trials that included 85 patients who received bi-weekly infusions of pegloticase for refractory chronic gout. Serum uric acid levels were measured prior to each infusion during the trial. The associations between the timing of the pegloticase infusion, uric acid levels, and the occurrence of infusion reactions were assessed by the research team.

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After analysis, the researchers found that of 22 participants who experienced an infusion reaction while receiving pegloticase, only 7 would have experienced a reaction if the infusion had been stopped following 2 sequential pre-infusion serum uric acid levels >6 mg/dL. In addition, they reported that only 2 participants would have had a reaction if the infusion had been stopped following a single pre-infusion serum uric acid level >6 mg/dL.

One key limitation of the study was the post hoc nature of the analysis.

“Stopping pegloticase in patients who have a rise in pre-infusion uric acid levels to above 6 mg/dL while on therapy would result in most [infusion reactions] being avoided,” the researchers wrote.

“For a commonly used, widely available, inexpensive blood test to reliably classify patients as ongoing therapeutic responders or non-responders prior to each infusion—allowing for therapy to be discontinued if warranted—is a powerful tool,” they concluded.

The authors of this study reported conflicts of interest with Horizon Pharma.